Replaced four occurrences of "an linear" by "a linear"

Suggested by Mohammud Atif.

doc/sphinx/developer_manual/libraries/lps/latex/lps-implementation-notes.tex

@@ -259,7 +259,7 @@ \subsubsection{well typedness constraints for other types}
 \section{Algorithms}
 
 We now define two operations on linear processes: removing (insignificant)
-parameters and removing constant parameters. Let $X(d:D)$ be an linear
+parameters and removing constant parameters. Let $X(d:D)$ be a linear
 process as defined in \ref{eq:lps_untimed}, or \ref{eq:lps_timed} and let $%
 \{d_{j_{1}},\cdots ,d_{j_{m}}\}$ be a set of insignificant parameters of $X$%
 . Then we define \textsc{RemoveParameters(}$p,\{d_{j_{1}},\cdots
@@ -274,7 +274,7 @@ \section{Algorithms}
 process is strongly bisimulation equivalent to $X(d:D)$\footnote{%
 A more formal definition of this is welcome.}.
 
-Let $X(d:D)$ be an linear process as defined in \ref{eq:lps_untimed}, or \ref%
+Let $X(d:D)$ be a linear process as defined in \ref{eq:lps_untimed}, or \ref%
 {eq:lps_timed} and let $\{d_{j_{1}},\cdots ,d_{j_{m}}\}$ be a set of
 constant parameters of $X$, given the state $\overline{d}:D$. Then we define 
 \textsc{RemoveConstantParameters}($p,\{d_{j_{1}},\cdots ,d_{j_{m}}\},%

doc/sphinx/user_manual/tools/release/lpsactionrename.rst

@@ -41,7 +41,7 @@ multi-action of the form ``a1|b`` will be replaced by ``b``. Instead of an
 action, ``a2`` may also be ``delta``. In this case, the action and the following
 process call are replaced by ``delta``.
 
-The renaming rules are applied from top to bottom to an linear process equation.
+The renaming rules are applied from top to bottom to a linear process equation.
 If no value for the variables in a rename rule can be found to match an action,
 the next rule is applied. If no rule applies the action is left untouched.
 Variables in different rename rules with the same variable names are independent

doc/sphinx/user_manual/tools/release/lpsparunfold.rst

@@ -5,7 +5,7 @@
 lpsparunfold
 ============
 
-The algorithm applies a transformation on data expressions of an linear process
+The algorithm applies a transformation on data expressions of a linear process
 specification (LPS), by which other tools (such as lpsparelm, lpsconstelm) can
 apply their transformations more effectively. In concrete, this tool unfolds a
 sort with associated constructor functions to a set of process parameters in the